The present invention relates to the field of copyright enforcement tools. More specifically, the present invention provides a mechanism for tracing usage of content.
Large amounts of copyrighted content are currently available in digital form. Such content includes movies, audio, and data files. There is great concern over the loss of control of this content. The cost of producing program material, such as entertainment movies, is considerable, whereas, the cost to the copyist is relatively low. Hence, movie piracy has become a substantial source of loss of revenue for the movie industry. Indeed, more than 3 billion dollars are lost to copyists annually, mainly in the form of bootleg video cassettes, peer-to-peer sharing of content and DVD discs.
Distribution of content subject to agreements regulating use is common. When these agreements are broken, content owners and distributors may loose money due to uncollected royalties and outright piracy. Content distribution and presentation industries have had a hard time providing an effective system for enforcing content use agreements after the content has been distributed. Enforcement has largely been done by hand audits of content presenters at great expense to both distributors and presenters.
Two approaches to thwarting piracy have been implemented by legitimate producers of movies and other types of material having commercial value, such as software: (1) injecting, into a protected medium, a signal that distorts the material in some manner when played, and (2) watermarking, by injecting a visible or invisible static symbol or mark that identifies the source of the original material.
Watermarking commonly is performed on a medium at the point of authoring of protected material. An example is at a post house or other facility at which the information-bearing medium is produced. However, once recorded, the watermark is fixed. Although the watermark may identify the source of authoring of the material, it will provide no information on the identity of an unauthorized copyist. It would be useful if the identity of the copyist was obtained from information gathered at the point of playback and copying. This may include such information as identification of the equipment used by the copyist and time of copying. Circuitry to provide this information at the playback unit, however, will increase the cost of the unit, a considerable disadvantage in this competitive industry. An objective of this invention is to produce a tracing signal at multiple points of use, that varies in dependence of, and is unique to, the copyist of a protected medium. Another objective is to do so without adding significant cost to the playback unit.
The protective signal furthermore should preferably be capable of being unpredictable, as predictability will enable a copyist either to filter out the signal, or alter it so as to provide a false designation of source. The protective system should also be robust, as any source of copying message injected into the signal stream should be recoverable in an environment having heavy transmission noise, and unintentional or intentional distortion. Furthermore, the sending message should be difficult to detect, modify or remove. The message content should be protected and difficult to decode, even if the transmitted bits identifying source are available.
Finally, the output stream must be legal to enable proper decoding in the appropriate domain. An additional objective of this invention is to produce use information, injected into the signal stream that is difficult for a copyist to detect or alter. The use information furthermore should preferably be able to be injected into any type of protected content, including audio and software, in addition to video.
U.S. Pat. No. 6,285,774 to Schumann et al. (herein after referred to as the '774 patent) and entitled “System and methodology for tracing to a source of unauthorized copying of prerecorded proprietary material, such as movies” discloses a system which addresses this issue. This patent enables the source of an unauthorized copy of an information-bearing medium, such as a video DVD, to be traced. As disclosed in the patent, the content stored on the medium is altered to include “running marks.” Running marks comprise holes in the content that may be encoded with a message designating where and when a single copy of the content was made. This patent is hereby included by reference for its' teaching of running marks. Typically, the message is spread throughout the content.
One problem with the '774 patent is that it does not address the situation where content is used multiple times, possibly on different pieces of equipment, possibly at different locations. For example, in the movie industry, content typically changes hands several times through daily shootings, the pre-release production process, mastering, replication, initial distribution, post distribution traffic. To solve this problem, a system that can allow a content owner to track multiple subsequent uses of content is needed.